1. Field of the Invention
One or more embodiments of the invention are related to the field of electrical cables. More particularly, but not by way of limitation, one or more embodiments of the invention enable a ground loop isolator for a coaxial cable, for example that blocks DC current but which allows a desired band of RF through the ground loop isolator, and which is small enough to fit in the areas where coupling of the desired electronic equipment is to occur.
2. Description of the Related Art
Standard coaxial cables may be utilized to connect high frequency electronic components together. Such a cable is shown in FIG. 1. As shown, coaxial cable 101 includes cable 102 and coaxial connector 103. When coaxial cable 101 is utilized as shown in FIG. 2, grounding problems may occur when an ungrounded television or digital video recorder (DVR) is coupled via the coaxial cable with a set top box (STB) for example. This may cause a “ground loop”, wherein undesired currents occur between two devices that should be, but are not at the same voltage, i.e., should be at the ground potential. In some cases, a voltage different of up to 60 volts or more may exist on the television or DVR since two-plug power cables may be utilized to power the devices, and the devices may have a significant potential with respect to ground potential voltage. When coupling a coaxial cable between the ungrounded television/DVR and the set top box, sparks may occur if the differential is high enough, thereby potentially causing a hazard.
Many ground loop isolators exist, but are generally large devices, for example that are not configured to fit in small areas such as are found behind television sets, DVRs and set top boxes. In addition, since many set top boxes are configured to output a radio frequency signal for channel 2, 3 or 4, ground loop isolators that utilize “chokes”, i.e., capacitor and inductor filters may limit the radio frequency signals in this range, which defeats the purpose of a ground loop isolator for coaxial cable scenarios, since the radio frequency at least in the range used between the set top box and the television may be blocked by the choke.
For at least the limitations described above there is a need for a ground loop isolator for a coaxial cable, for example that blocks DC current but which allows a desired band of RF through the ground loop isolator, and which is small enough to fit in the areas where coupling of the desired electronic equipment is to occur.